Air-o-matic spot welder



June 7, 1938.

E. G. BIEDERMAN 2,120,141 AIR-O-MATIC SPOT WELDER Filed Au 27, 1936 3 Sheets-Sheet 1 INVENTOR.

ATTORNEYS.

June 7, 1938. BlEDERMAN 2,120,141

AIR-O-MATIC SPOT WELDER IN VENT OR.

ATTORNEYS.

June 7, 1938. E. G. BIEDERMAN AIR-Q'MATIC SPOT WELDER Filed Aug. 27, 1936 5 Sheets-Sheet 3 r INVENTOR. BY 5242/ J Elk/(0774?;

ATTORNEYS.

Patented June 7, 1938 PATENT OFFICE AIR-O-MATIC SPOT WELDER Edward G. Biederman, Detroit, Mich., assignor to GeneralMotors Corporation, Detroit, Mich a corporation of Delaware Application August 27, 1936, Serial No. 98,217

Claims.

This invention is an improvement in my copending application, Serial No. 41,515, filed September 21, 1935. In that application, there is described and claimed a multiple spot welder in 5 which the welds are successively made by successive shots of fluid distributed to .successive electrode-control cylinders by means of a rotating distributor. This distributor, at each shot of fluid distributes fluid pressure into a cylinder that operates the switch in the primary circuit. 7

The improvement of the present apparatus consists in substituting shots of fluid to return the pistons as well as to push the pistons down to bring the electrodes together. The spring returns in my prior apparatus have not been found entirely satisfactory. There are other detailed improvements in the construction of the distributor plate.

. In the drawings: Fig. 1 is a view largely a plan view of the distributor and the novel arrangement for distributing fluid from one side of one piston to the opposite side of the other piston. 4

Fig. 2 is a vertical section through tributor.

Fig. 3 is a section on the line 3--3 of Fig. 1.

1 Fig. 4 is a section on the line 4-4 of Fig. 2

the dis- Fig. 5 is a diagrammatic view of the apparatus.

Turning to Fig. 5, the movable electrodes are shown at I. These are operated each by an air cylinder and piston 2 which is fed with shots of fluid through the lines 3 that connect with the distributing plate 4. The distributing plate or ring 4 as shown in Fig. 1 is drilled with a plurali- 35 ty of sets of holes or ports 5. Instead of milling a slot as in my prior application, I get a cheaper construction by drilling an opening 6 in from the circumference of the plate and then drilling three or more holes 511, 5b, and 50 from the top.

A fourth hole I is also drilled in from the top.

The series of holes 511, 5b and 5c is for distributing fluid from the rotating distributor arm 8.

Fluid under pressure enters at 9, passes through the passage I0, thence around the bushing and 45 through the ports Ii into the passageway l2. At'

the end of the passageway I2, a runaround passage i3 brings the fluid to the large port M which is adapted to momentarily register with the set of perforations 5a, 5b and 50 to give the passageway 50 6 a shot of compressed fluid. The shot 01' compressed fluid is distributed through the pipe' 3 to the appropriate cylinder. Hence, as the distributor arm rapidly revolves, successive shots of fluid go to successive pipes 3 and into successive 5 cylinders. This is the principle of the apparatus described in my, prior application Serial No. 41,515 except for the way the openings are drilled in the distributor plate.

The pressure backs up in the passage 6 and also passes through the port I which has a metering 5 valve IS. The fluid under pressure backs up into the passage l6 and back down the rotatable shaft 11, out through the port it, up through the pipe i9 (see Fig. 5) to the contactor cylinder 20 where it serves to actuate the piston 2| that forces the 10 cam 22 upwardly to throw the switch 23 in the primary circuit. As soon as the cam passes the arm 24, the spring 25 pulls the switch open. The timing of the circuit is regulated by the adjustment of the metering valve l5. It also, of course. 15 depends upon the spring tending to return the contactor cam and pressure of the fluid. Nothing is claimed for this in the present application asv that is described in my prior application except for the metering pin.

The novel matter here is: the unique way in which one single shot of fluid serves not only to lift the piston but after the piston is raised a given distance, this shot of fluid pushes the piston in the next cylinder in operating succession down 5 by reason of the transfer pipe 26 that passes from under one piston to above the other piston. Hence, when the electrode thathas just delivered a weld has been lifted a given distance, it vents I compressed fluid into the next cylinder, in order 30 of operating succession, to bring the next pair of electrodes onto the work. This is not only a very simple way of arranging and timing the fluid in successive cylinders, but it obviates considerable complications in piping that would be other- 5 wise necessary (if indeed practical) leading from the distributor and with correspondingly additional number of ports on the face of the distributor plate.

This improvement afiords a positive, high 40 pressure fluid to quickly and positively separate the electrodes. It is found in actual practice that sometimes the springs stick and fail to work efliciently. I appreciate that itis common in welders to use hydraulic and air pressure for both bringing the electrodestogether and separating. them, but I do believe that the arrangement of my distributor and the venting of the air from one cylinder to the next to make one line of ports do on the distributor is entirely new.

What I claim is:

1. In a multiple spot welder, the combination of a plurality of sets of electrodes, a cylinder and piston in connection with one electrode oi each set, means for supplying fluid under pressure, a

distributor provided with ports one connected with each separate cylinder and including a movable distributor member charged with compressed fluid from said source and means for supplying fluid from each of said ports to opposite sides of two pistons to positively bring one set of electrodes together by fluid pressure and positively separate another set of electrodes by fluid pressure.

2. In a multiple spot welder, the combination of a plurality of sets of electrodes, a cylinder and piston in connection with one electrode of each set, means for supplying fluid under pressure, a distributor provided with a port connected with each separate cylinder and including a movable distributor member charged with compressed fluid from said source and means for transferring and venting the fluid charge from one side of one piston to the opposite side of the piston in the cylinder of the next set of electrodes in the sequence of operations.

3. In a multiple spot welder, the combination of a plurality of sets of electrodes, a cylinder and piston in connection with one electrode of each set, means for supplying fluid under pressure, a distributor provided with a port connected with each separate cylinder and including a movable distributor member charged with compressed fluid from said source and means for transferring the fluid pressure from below one piston to above the piston in the next cylinder in succession of operatlon.

4. In a multiple spot, welder, the combination of a plurality of sets of electrodes, a cylinder and piston in connection with one electrode of each set, means for supplying fluid under pressure, a distributor provided with a port connected with each separate cylinder and including a movable distributor member charged with compressed fluid from said source and a transfer pipe leading from one side of the piston in one cylinder to the opposite side of the piston in the cylinder neXt in succession of operation whereby a single shot of fluid delivered from the distributor lifts one set of electrodes and presses together the succeeding set of electrodes in timed relation.

5. In. a multiple spot welder, a plurality of sets of electrodea'a plurality of cylinders and pistons, one cylinder and piston connected to each set of electrodes for bringing them together and separating them, means for supplying fluid under pressure, a distributor in the form of a stationary member provided with a plurality of ports and a moving member charged with compressed fluid which passes over the said ports to deliver shots of compressed fluid to each port, the said ports having connections with the cylinders arranged to, in proper sequence, deliver a charge. of fluid to move the piston of one cylinder to separate the electrodes and move the piston of another cylinder to bring the electrodes together.

G. BIEDERMAN. 

